A new method for personal aerosol sampling has been conceived by two members of the research team. The overall objective of this research is to incorporate a new concept into a personal aerosol sampler for the assessment o f w orker exposure in indoor and outdoor occupational environments contaminated with airborne dust and/or microorganisms. The major features of this new small sampler are its low ambient wind sensitivity and high filter collection uniformity. The new device will be developed for personal sampling of the respirable, thoracic and/or inhailable fractions of inert dust particles and/or airborne microorganisms such as bacteria, fungi and (possibly) pollen. The sampling flow rate will be that of battery-operated personal sampling pumps. The physical aspects of the personal sampler development will be studied in the wind tunnel of the investigators' Dust Sampler Evaluation Facility. The sampler's overall physical efficiency and its filter collection uniformity will be evaluated with liquid and solid biologically-inert particles ranging from about 5 to about 100 m in aerodynamic diameter. The biological aspects and the physical aspects of sampling from near-stagnant air environments will be studied in the Bio-aerosol Sampler Evaluation Facility. Commercially available and the applicants' newly-developed stationary bio-aerosol samplers will be used to evaluate the new personal aerosol sampler with spores and vegetative cells. Tests with fungi-type bacteria and fungal spores will simulate occupational exposures in industrial and agricultural environments. Standard and newly-developed microbiological methods will differentiate the sampler's biological component from the non-biological one, and will determine the percentage of viable and/or culturable microorganisms. The applicability of these analytical methods for the new personal sampler will be explored and sampler prototypes will be evaluated in the field -- in industrial, agricultural and health-care environments. These studies will be performed in collaboration with other research teams by joining their ongoing field measurements. The performance of the new sampler will be compared with that of several commercially available personal and ambient samplers. The ACGIH criteria for representative sampling of airborne dust particles and microorganisms and the NIOSH recommendations on current priorities in aerosol characterization will be taken into account in the development of the new device.